The consortium of investors seeking to take over Severn Trent offered just under 20 pounds per share for the British water company, valuing it at around 4.7 billion pounds ($7.17 billion), a source told Reuters on Wednesday.
This would represent a premium of 10 percent to Severn Trent's closing share price on Monday of 18.25 pounds, the day before news of a bid emerged, and a 21 percent premium to the six month average share price.
Shares in Severn Trent closed up 0.63 percent at 20.90 pounds.
The source, who spoke on condition of anonymity, said the offer would represent a premium of around 30 percent to the water company's regulated asset base (RAB), in line with historic transactions in the region of 25 to 30 percent above RAB.
Severn Trent and representatives for the consortium declined official comment.
Severn Trent said on Tuesday it had been approached by a consortium including Borealis infrastructure, the Kuwait Investment Office and Britain's Universities Superannuation Scheme, after reports that it could be the target of an offer of between 22.5 pounds and 23 pounds a share.
The board of the FTSE 100 company, which supplies 7.7 million people in Britain with drinking water, subsequently rejected a preliminary takeover approach giving no details of the offer, but said it "completely fails to recognise the existing and potential value of Severn Trent."